//C16:16.15:qsorter.c -- qsort().
#include <stdio.h>
#include <stdlib.h>

#define NUM  40
void fillarray(double ar[], int n);
void showarray(const double ar[], int n);
int mycomp(const void *p1, const void *p2);

int main(void)
{
    double vals[NUM];
    fillarray(vals, NUM);
    puts("Random list: ");
    showarray(vals, NUM);

    qsort(vals, NUM, sizeof(double), mycomp);

    puts("\nSorted list: ");
    showarray(vals, NUM);
}

void fillarray(double ar[], int n)
{
    int index;
    for (index = 0; index < n; index++)
    {
        ar[index] = (double)rand() / ((double)rand() + 0.1);
    }
}

void showarray(const double ar[], int n)
{
    int index;
    for (index = 0; index < n; index++)
    {
        printf("%9.4f ", ar[index]);
        if(index % 6 == 5)
        {
            putchar('\n');
        }
    }

    if(index % 6 != 0)
    {
        putchar('\n');
    }
}

int mycomp(const void *p1, const void *p2)
{
    const double *a1 = (const double*)p1;
    const double *a2 = (const double*)p2;

    if(*a1 < *a2)
    {
        return -1;
    }
    else if(*a1 == *a2)
    {
        return 0;
    }
    else
    {
        return 1;
    }
 }